Full-body scanners installed at Dulles

Full-body security scanners will be used at Dulles International Airport starting next week, ending a years-long rollout of the technology that has prompted privacy concerns because of the revealing images it displays.

The devices, dubbed virtual strip searches because of the outlines of the unclothed human body they produce, had been slow to catch on at some airports partly because of privacy concerns raised by some members of Congress and civil liberties groups.

The scanners will be used in certain areas of Dulles, but officials would not be specific because of security reasons. They will not entirely replace conventional equipment.

"Each airport is different, and we've been working to get them in use nationwide as we work to keep the traveling public safe," said Lauren M.W. Gaches, a spokeswoman for the Department of Homeland Security.

Umar Farouk Abdulmutallab is accused of boarding a Northwest flight in Amsterdam with explosives hidden in his underwear.

There are 341 imaging technology machines being used at 67 airports, according to the TSA. Authorities are planning to install about 110 more by year's end. About 13,000 scanning stations are in use nationwide.

Reagan National and Baltimore-Washington International Marshall Airport started using the body-imaging technology in January and June, respectively.

Those airports' scanners, which use electromagnetic waves to probe objects within an inch of the skin, are more circular in shape and a bit taller and thinner than the machines at Dulles, which use a type of X-ray beam.

When walking through the security screen, passengers stand inside a partially enclosed boxlike tube with their hands in the air for about five seconds while a low dose of radiation washes over them. Images are transmitted to a nearby control room. Security agents at checkpoints do not have access to the images, and the TSA says it deletes all images after they are reviewed.

Passengers who wish to opt out of the scan must submit to a full-body pat-down by a TSA officer.

Federal officials estimate that less than 1 percent of fliers decline the scan.